Quantum Droplets Discovered in a Semiconductor

Quasiparticles are interesting things in physics, as they are actually small groups of individual particles, which for one reason or another have come together to behave as one. One example is an exciton, which is actually an electron and the positively charged hole it leaves behind. Researchers at NIST and the University of Marburg recently created a quantum droplet containing about five electrons and holes.

In semiconductors, it is not unusual for electron-hole droplets to form, but they typically contain thousands to millions of pairs. The smaller droplets the researchers discovered were made with an ultrafast red laser pulsing at about 100 million times a second on gallium-arsenide. Initially the pulses just formed excitons, but as the intensity grew the pairing within the excitons fell apart and the electrons and holes collected together, forming the new quasiparticle.

With a lifespan of only about 25 picoseconds (0.000000000025 seconds), we will likely not be seeing any technology built around these. However that is long enough to perform optical studies, to learn how light interacts with highly correlated states of matter, and that may influence future optoelectronics.